The present invention relates to the alignment of vehicle components relative to one or more features of a vehicle, and in particular, to methods and apparatus for utilizing a vehicle wheel alignment system to facilitate adjusting the alignment of sensors associated with forward looking vehicle collision avoidance systems relative to a determined thrust line of the vehicle.
Machine vision vehicle wheel alignment systems have been in use by the vehicle service industry for several years. A typical machine vision vehicle wheel alignment system, such as the Series WA400 wheel alignment system, configured with the Hawkeye Alignment sensors manufactured by Hunter Engineering Co. of Bridgeton, Mo. consists of a console unit, imaging sensors or cameras, and optical targets. The console unit contains a computer or processor configured with suitable image processing and vehicle wheel alignment software applications, and incorporates various conventional operator interfaces, such as a keyboard, a mouse, a printer, and a display device. The imaging sensors or cameras are operatively coupled to the computer or processor, and the optical targets are disposed in the field of view of the imaging sensors or cameras, typically mounted to the wheels of a vehicle undergoing an alignment inspection.
Commonly, to view the left and right sides of a vehicle, at least one imaging sensor or camera is disposed with a field of view oriented to observe the left side of the vehicle, and at least one imaging sensor or camera is disposed with a field of view orientation to observe the right side of the vehicle. The field of view of each imaging sensor or camera encompasses one or more wheels of the vehicle. In alternative configurations, two imaging sensors or cameras are provided on each side of the vehicle, each having a field of view encompassing at least one of the two vehicle wheels on the respective side of the vehicle, i.e. a left front, left rear, right front, and right rear wheel, respectively. To facilitate vehicle wheel alignment, optical targets are mounted on the vehicle wheels, and observed by the imaging sensors or cameras. The optical targets preferably have predetermined features which are identified in images obtained by the imaging sensors or cameras, and which facilitate a determination of the position and orientation of the optical targets in three dimensional space. The image processing may either take place in the imaging sensor or camera modules, or in the console computer or processor. Once the position and orientation of each optical target is determined, the position and orientation of the associated vehicle wheel can be determined, and corresponding, the various vehicle wheel alignment angle measurements may be either determined or calculated by the computer or processor using suitable mathematical algorithms. Vehicle wheel alignment angle measurements typically include a measure of camber, caster, and toe angles for each vehicle wheel, as well as the spatial position and orientation of the vehicle centerline and the vehicle rear thrust line.
It is becoming increasingly common for automotive vehicles to be equipped with various external sensor systems, such parking assist cameras, backup cameras, lane departure warning systems, blind spot detections systems, adaptive cruise control systems, and forward-looking collision avoidance radar components. Many of these external sensor systems require precise positioning and/or alignment of an associated field of view for proper operation. For example, adaptive cruise control system and collision avoidance radar components typically operate in either a frequency modulation (FM) or continuous wave (CW) mode to transmit a forward-looking signal from an antenna typically located in the front grill area of an automobile. The collision avoidance radar then determines from the return signal received by the antenna a distance an object causing the return signal is located from the automobile and the rate of closure of the object. Adaptive cruise control systems in the United States of America are currently configured to operate within a 76-77 GHz frequency band allocated by the Federal Communications Commission (FCC) for collision avoidance radar systems. However, other collision avoidance systems may be constructed which operate within different portions of the electromagnetic spectrum, for example, utilizing infrared or visible light lasers to obtain information about objects in the path of a vehicle, or alternatively, utilizing ultrasonic signals or cameras.
To obtain an accurate measure of the distance between the vehicle on which the collision avoidance components are mounted, and an observed object in the path of the vehicle, it is necessary to ensure that the object is in fact observed along the same vector as the vehicle is traveling, which is typically the vehicle rear thrust line for straight-line motion. In other words, it is necessary to ensure that signals emitted by a collision avoidance system, or field of view of an associated camera, are aligned along the same vector as the vehicle is traveling. Any misalignment between the transmission/observation vector and the direction of vehicle travel may result in misidentification of approaching objects, a miscalculation of the distances between the vehicle and the object, and accordingly, a miscalculation of the rate of closure between the two. Depending upon the severity of the miscalculation, the collision avoidance system might fail to recognize an impending collision, or in the case of adaptive cruise control systems, might signal a reduction in vehicle speed which is less than that which is actually required to safely avoid a collision between the vehicle and the approaching object.
Conventionally, the manufacturer of the vehicle external sensor system, such as a collision avoidance system, provides a vehicle service apparatus or alignment fixture specifically designed to facilitate the alignment of the signal emitting and receiving components. For example, a collision avoidance system alignment fixture is placed in front of the vehicle, and configured with components to facilitate a precise placement and orientation of the alignment fixture relative to the vehicle as specified by the vehicle manufacturer. These may include alignment marks onto which lasers are projected from laser pointers mounted to fixed positions on the vehicle structure (or in converse, may include mounting points for lasers to project towards alignment marks on the vehicle). Alternatively, the collision avoidance system alignment fixture may include mounting points to receive traditional transducer-based vehicle wheel alignment sensor heads or machine vision optical targets which are then observed by a suitably configured vehicle wheel alignment system to guide the operator to properly place and orient the fixture. Once the fixture is properly placed and oriented as specified by the vehicle manufacturer, the operator proceeds with a calibration procedure for the collision avoidance system (or other external sensing system) as specified by the vehicle manufacturer. These procedures typically requires that the vehicle sensor system be activated on-board the vehicle by the operator to observe the alignment fixture and to provide appropriate feedback for adjustment and calibration. Alternatively, a laser may be projected from the alignment fixture towards a target or mirror associated with the vehicle sensor system, and adjustments made to the vehicle sensor system to reflect the laser back to a specified point on the alignment fixture. In some cases, an OEM vehicle-specific scan tool or external control unit is required to be coupled to the vehicle ECU by the operator in order to initiation and or complete the adjust and calibration procedures.
U.S. Pat. No. 7,382,913 B2 to Dorrance et al., herein incorporated by reference, describes a method for facilitating the placement of a vehicle collision avoidance system alignment fixture relative to the direction of travel of an associated vehicle, using a machine vision vehicle wheel alignment system, cameras, and associated optical targets, thereby eliminating the need for vehicle service centers to either delay acquiring machine vision vehicle wheel alignment systems or maintaining both a machine vision vehicle wheel alignment system for vehicle wheel alignment measurements and a conventional transducer-based vehicle wheel alignment system specifically for the purposes of aligning vehicle collision avoidance system fixtures.
In order to utilize the machine vision vehicle wheel alignment system features, the '913 Dorrance et al. method requires the placement of an additional set of optical cameras on the vehicle collision avoidance system alignment fixture, to enable the machine vision vehicle wheel alignment system to observe wheel mounted optical targets from the position of the fixture, and to direct to operator to carry out any necessary placement adjustments for the fixture prior to adjusting the alignment of a collision avoidance system components on the vehicle.
Accordingly, it would be advantageous to provide a low cost method and simplified apparatus to facilitate the placement of a vehicle service apparatus, such as a headlight aiming device, or alignment fixtures for vehicle external sensor systems such as Intelligent Vehicle Highway Systems, relative to the thrust line of a vehicle undergoing a vehicle service procedure, without directly using components of a vehicle wheel alignment system mounted to the vehicle service apparatus or alignment fixture, thereby eliminating the need for additional or supplemental machine vision cameras, image processing procedures, optical targets, or conventional alignment angle transducers to complete the vehicle service procedure.
It would be advantageous to provide a low cost method and simplified apparatus to facilitate the placement of a of a vehicle service apparatus, such as a headlight aiming device, or alignment fixtures for vehicle external sensor systems such as Intelligent Vehicle Highway Systems, relative to the surface on which the vehicle undergoing a vehicle service procedure is currently resting, without directly using components of a vehicle wheel alignment system mounted to the vehicle service apparatus or alignment fixture, thereby eliminating the need for additional or supplemental machine vision cameras, image processing procedures, optical targets, or conventional alignment angle transducers to complete the vehicle service procedure, as well as compensating for any variations in the levelness of the surface on which the vehicle is disposed.
It would be further advantageous to provide a vehicle service system, such as a vehicle wheel alignment system, with the capability to communicate with an on-board computer or control system (ECU) of a vehicle, in order to either initiate or carry out, an OEM calibration or alignment procedure associated with an external sensor system of the vehicle once a vehicle service apparatus or alignment fixture has been properly positioned and oriented in proximity to the vehicle, thereby reducing the steps an operator must carry out to complete the procedure and eliminating the need for additional scan tools or interface devices.